Methods for selective deposition utilizing n-type dopants and/or alternative dopants to achieve high dopant incorporation

ABSTRACT

A method for forming a doped layer is disclosed. The doped layer may be used in a NMOS or a silicon germanium application. The doped layer may be created using an n-type halide species in a n-type dopant application, for example.

FIELD OF INVENTION

This application is a non-provisional of, and claims priority to and thebenefit of, U.S. Provisional Patent Application No. 62/879,980, filedJul. 29, 2019 and entitled “METHODS FOR SELECTIVE DEPOSITION UTILIZINGN-TYPE DOPANTS AND/OR ALTERNATIVE DOPANTS TO ACHIEVE HIGH DOPANTINCORPORATION,” which is hereby incorporated by reference herein.

FIELD OF INVENTION

The present disclosure generally relates to selective deposition ofsemiconductor films on substrates. More particularly, the disclosurerelates to selective deposition utilizing dopants. The dopant precursorsmay include hydrides and halogenated Group V.

BACKGROUND OF THE DISCLOSURE

For logic applications, FinFET transistors have been made by epitaxialdeposition processes. Dopants have been used to match a particularchannel type, such as an n-type doped layer for NMOS applications.Particular n-type layers formed may include silicon carbide (SiC),silicon carbophosphine (SiCP), and silicon phosphine (SiP), for example.

Formation of the layers may be difficult when growing on asubstitutional lattice site. There may be issues that may result insacrificing at least one of selectivity, growth rate, dopantconcentration, and resistivity of the grown layers. For example, toachieve particular selectivity for the layer, this may require the flowof a particular chemistry or the reduction in a process temperature thatcould adversely affect the growth rate of the layer and/or dopantincorporation.

As a result, it is desired to develop a process that allows for anoptimal growth rate of a doped layer, while achieving a desiredselectivity and geometry for the doped layer.

SUMMARY OF THE DISCLOSURE

This summary is provided to introduce a selection of concepts in asimplified form. These concepts are described in further detail in thedetailed description of example embodiments of the disclosure below.This summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended to be used tolimit the scope of the claimed subject matter.

A method for forming a contact layer is disclosed. The method maycomprise: cleaning a device on a semiconductor substrate of any oxides,the semiconductor substrate being disposed on a susceptor in a reactionchamber; stabilizing a temperature of the reaction chamber; flowing ahalide precursor onto the device, the halide precursor comprises atleast one of: hydrogen fluoride (HF); hydrogen chloride (HCl); hydrogenbromide (HBr); hydrogen iodide (HI); chlorine (Cl₂); fluorine (F₂);bromine (Br₂); or iodine (I₂); flowing a silicon precursor onto thedevice, the silicon precursor comprises at least one of: silane (SiH₄);dichlorosilane (DCS); disilane; or trisilane; and flowing a dopantprecursor onto the device, the dopant precursor comprises at least oneof: PCl₃; PCl₅; PBr₃; PBr₅; PI₃; PI₅; AsCl₃; AsCl₅; AsBr₃; AsBr₅; AsI₃;AsI₅; SbCl₃; SbCl₅; SbBr₃; SbBr₅; SbI₃; SbI₅; arsine (AsH₃); orphosphine (PH₃); wherein the halide precursor prevents deposition onto adielectric layer disposed on the semiconductor substrate; wherein thesilicon precursor and the dopant precursor react to form a contactlayer; wherein any of the flowing steps are repeated to form a desiredthickness of the contact layer.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

These and other features, aspects, and advantages of the inventiondisclosed herein are described below with reference to the drawings ofcertain embodiments, which are intended to illustrate and not to limitthe invention.

FIG. 1 is a cross-sectional illustration of a NMOS device formed inaccordance with at least one embodiment of the invention.

FIG. 2 is a process flow diagram in accordance with at least oneembodiment of the invention.

FIG. 3 illustrates an apparatus in accordance with at least oneembodiment of the invention.

It will be appreciated that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help improve understanding ofillustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

The illustrations presented herein are not meant to be actual views ofany particular material, structure, or device, but are merely idealizedrepresentations that are used to describe embodiments of the disclosure.

For FinFET applications, a contact layer may be needed on top of a Fin.Contact layers may also be grown for silicon germanium (SiGe)applications as well. For contact layers in particular NMOSapplications, it may be desirable to incorporate high levels of n-typedopant. Such may increase the electrically active behavior of thecontact layer.

FIG. 1 illustrates a device 100 in accordance with at least oneembodiment of the invention. The device 100 may comprise: a Fin 110; ashallow trench isolation (STI) layer 120; a contact layer 130; and agate 140. The Fin 110 may be a stack of lateral nanowires comprising atleast one of: silicon, germanium, silicon germanium, or combinationsthereof. The STI layer 120 may comprise a dielectric material, such assilicon oxide, silicon oxynitride, silicon oxycarbon, and combinationsthereof, for example. The gate 140 may also comprise an oxide material,such as hafnium oxide or aluminum oxide, for example.

The contact layer 130 may comprise at least one of: silicon phosphine(SiP); silicon arsenide (SiAs); silicon antimonide (SiSb); orcombinations thereof, for example. The contact layer 130 may be grownwith a particular crystallographic orientation, such as a (111)direction in accordance with the Miller indices notation.

In growing the contact layer 130, an additional issue may arise with theselectivity, as it may be difficult to grow the contact layer 130without depositing a layer on the exposed dielectric material of the STIlayer 120. In other applications, the way to achieve such selectivitymay be to increase a flow of hydrogen chloride (HCl) or to decrease atemperature of the process. However, such may not be possible in thisapplication as increasing a flow of HCl or decreasing a processtemperature may inhibit the growth rate of the contact layer 130 and/oradversely affect a doping level incorporated in the contact layer 130.

In order to achieve a proper growth rate and doping level, FIG. 2illustrates a process 200 for growing a contact layer 130. The process200 may comprise: a preclean step 210; a temperature stabilization step220; a halide precursor flow step 230; a silicon precursor flow step240; a dopant precursor flow step 250; and a repeat cycle 260. Theprocess 200 may occur in a deposition apparatus comprising: a reactionchamber, a heating element, a susceptor, and multiple gas sources.

The preclean step 210 may comprise a process to remove any oxides on adevice prior to growing the contact layer 130. The preclean step 210 mayincorporate flow of chemical and sublimation as described in U.S. Pat.No. 10,053,774, entitled “Reactor System for Sublimation of Pre-CleanByproducts and Method Thereof,” which is hereby incorporated byreference. Alternatively, the preclean step 210 may flow NF₃ and ammonia(NH₃) chemistry with remote plasma. The preclean step 210 may take placeat a temperature range between 500° C. and 800° C., between 550° C. and700° C., or between 600° C. and 650° C.

The temperature stabilization step 220 may be required if the precleanstep 210 requires a different temperature than that required to form thecontact layer 130. The temperature stabilization step 220 may result ina temperature of a reaction chamber ranging between 300° C. and 800° C.,between 400° C. and 650° C., or between 450° C. and 550° C.

The halide precursor flow step 230 may comprise a flow of at least oneof: hydrogen fluoride (HF); hydrogen chloride (HCl); hydrogen bromide(HBr); hydrogen iodide (HI); chlorine (Cl₂); fluorine (F₂); bromine(Br₂); iodine (I₂); or combinations thereof. The purpose of the halideprecursor flow step 230 is to allow for selective deposition of thecontact layer 130 onto the Fin 110, and not the STI layer 120. However,the halide precursor flow step 230 should not be so great as to inhibitthe growth rate of the contact layer 130.

The silicon precursor flow step 240 may comprise a flow of at least oneof: silane (SiH₄); dichlorosilane (DCS); disilane; trisilane;trichlorosilane; or combinations thereof. The silicon precursor willdeposit onto the Fin 110, where it will react to form the contact layer130.

The dopant precursor flow step 250 may comprise a flow of at least oneof: a phosphoric halide, such as PCl₃, PCl₅, PBr₃, PBr₅, PI₃, or PI₅; anarsenic halide, such as AsCl₃, AsCl₅, AsBr₃, AsBr₅, AsI₃, or AsI₅; anantimony halide, such as SbCl₃, SbCl₅, SbBr₃, SbBr₅, SbI₃, or SbI₅; or ahydride, such as arsine (AsH₃) or phosphine (PH₃), for example. Thedopant precursor flow step 250 may comprise co-flowing or alternatelyflowing multiple dopant sources chosen among the ones listed above.

Prior approaches may have used phosphine or arsine as a dopant source,but such may result in safety issues in terms of handling and deliveryto the reaction chamber due to the high vapor pressures involved. Byincluding at least one of the dopant precursors listed above, thesurface chemistry may be modified to incorporate more of the n-typedopant in an electrically active lattice position, while operating in asafe regime.

The method 200 may also include the repeat cycle step 260 in order toform a film of a desired thickness.

As a result of the steps in the method 200, a lower temperature andpressure for the reaction chamber may be possible. The temperature mayrange between 400° C. and 800° C., between 550° C. and 700° C., orbetween 600° C. and 650° C. The pressure may range between 0.1 and 760Torr, between 10 and 200 Torr, or between 30 and 100 Torr.

Furthermore, the process 200 may result in a contact layer formed withsilicon phosphine (SiP), for example, that has a high phosphorouscontent and electrically active characteristic without going into adefect state. In addition, a high level of dopant incorporation may bepossible due to the process 200.

FIG. 3 illustrates an apparatus 300 for forming a device in accordancewith at least one embodiment of the disclosure. Apparatus 300 includes areaction chamber 302, a first gas source 304 configured to provide afirst gas to reaction chamber 302, a second gas source 306 configured toprovide a second gas to reaction chamber 302; and a susceptor 308configured to hold a semiconductor substrate on which a device isformed. Apparatus 300 can further include a gas distribution device 310to provide one or more gases to reaction chamber 302. Additionally,apparatus 300 can include a controller 312 to, for example, control gasflowrates, reaction chamber pressure, reaction chamber temperature,and/or the like. Apparatus 300 can be configured to perform a method asdescribed herein.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the aspects and implementations in any way. Indeed, for thesake of brevity, conventional manufacturing, connection, preparation,and other functional aspects of the system may not be described indetail. Furthermore, the connecting lines shown in the various figuresare intended to represent exemplary functional relationships and/orphysical couplings between the various elements. Many alternative oradditional functional relationship or physical connections may bepresent in the practical system, and/or may be absent in someembodiments.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. Thus, the various acts illustrated may beperformed in the sequence illustrated, in other sequences, or omitted insome cases.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems, and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

1. A method of forming a contact layer on a Fin disposed on asemiconductor substrate, the method comprising: cleaning a device on asemiconductor substrate of any oxides, the semiconductor substrate beingdisposed on a susceptor in a reaction chamber; stabilizing a temperatureof the reaction chamber; flowing a halide precursor onto the device, thehalide precursor comprises at least one of: hydrogen fluoride (HF);hydrogen chloride (HCl); hydrogen bromide (HBr); hydrogen iodide (HI);chlorine (Cl₂); fluorine (F₂); bromine (Br₂); or iodine (I₂); flowing asilicon precursor onto the device, the silicon precursor comprises atleast one of: silane (SiH₄); dichlorosilane (DCS); disilane; ortrisilane; and flowing a dopant precursor onto the device, the dopantprecursor comprises at least one of: PCl₃; PCl₅; PBr₃; PBr₅; PI₃; PI₅;AsCl₃; AsCl₅; AsBr₃; AsBr₅; AsI₃; AsI₅; SbCl₃; SbCl₅; SbBr₃; SbBr₅;SbI₃; SbI₅; arsine (AsH₃); or phosphine (PH₃); wherein the halideprecursor prevents deposition onto a dielectric layer disposed on thesemiconductor substrate; wherein the silicon precursor and the dopantprecursor react to form a contact layer; and wherein any of the flowingsteps are repeated to form a desired thickness of the contact layer. 2.The method of claim 1, wherein the cleaning step is performed at atemperature between 300° C. and 800° C., between 400° C. and 650° C., orbetween 450° C. and 550° C.
 3. The method of claim 1, wherein the stepof stabilizing comprising stabilizing the temperature to a temperatureranging 400° C. and 800° C., between 550° C. and 700° C., or between600° C. and 650° C.
 4. The method of claim 1, wherein a pressure of thereaction chamber ranges between 0.1 and 760 Torr, between 10 and 200Torr, or between 30 and 100 Torr.
 5. The method of claim 1, wherein thecontact layer formed has a crystallographic orientation of (111).
 6. Anapparatus for forming a device, comprising: a reaction chamber; a firstgas source configured to provide a first gas to the reaction chamber; asecond gas source configured to provide a second gas to the reactionchamber; and a susceptor configured to hold a semiconductor substrate onwhich a device is formed; wherein the apparatus is configured to performthe method of claim 1.